I would love to be able to quickly lock and unlock tasks. Locking has become essential as we've begun to add more and more dependencies. If you don't have your tasks locked, then you can really screw up a project by changing the end date of one task. Any user could unknowingly move a cascade of 15 tasks just because they change a date in Kanban view. If we could easily lock dates, I would just lock them by default and only unlock when we need to make changes in plan view.
If this isn't possible, at least allow us to unlock a task and change the date without having to save. I hear a lot of complaints about that because people open a task, put it in edit mode, change the date, click save, realize the tasks is locked, then uncheck the lock and change the date again only to realize that they have to save first before changing the date. Essentially, it requires two saves, but could end up being 7 or 8 frustrating steps if you don't understand what's going on. I think a quick lock/unlock feature would address this issue.